You are asking about ORM, which can't be explained in a couple of lines. Simply put ORM are Object Relation Mapping tools like Hibernate/EntityFramework that exposes tables as Objects and do CRUD operations in transparent hence giving developers flexibility to focus on developing business usecases instead of digging the nitty gritty of how to fetch/save/update/delete data in the database.
There are books avaiable and even articles on CodeProject that can give you concept and a push to start with.
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